A heat treatment free 6n01 aluminum alloy and a preparation method and application thereof

Abstract

The present application relates to the technical field of aluminum alloy, and particularly provides a heat treatment free 6N01 aluminum alloy, a preparation method and application thereof, the 6N01 aluminum alloy is an extruded profile obtained by compacting, sintering, extruding and aging treatment of composite powder cold welding particles; the composite powder cold welding particles are obtained by ball milling of composite powder composed of aluminum powder and carbon nanotube and Mg and Si, and the aging treatment refers to transient aging precipitation during the natural cooling process after alloy phase extrusion; wherein, the content of Mg in the composite powder cold welding particles is 0.5-0.7wt%, the content of Si is 0.6-0.7wt%, the content of carbon nanotube is 0.5-1.2vol%, and the content of trace alloying elements is not higher than 0.5wt%. For the 6N01 aluminum alloy long profile with a single length of 26-30 meters for high iron, the present application can greatly shorten the delivery cycle and reduce the cost, and has good practical engineering significance and economic value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy, in particular to a heat treatment-free 6N01 aluminum alloy and a preparation method and application thereof. BACKGROUND

[0002] 6N01 is an Al-Mg-Si series aluminum alloy, which has a small alloy composition, a medium-low strength mechanical property, a good processing forming property, a corrosion resistance, a fatigue resistance and a welding performance, and is widely used in rail transit vehicles and the like. The extruded profile is the most widely used structural application form of 6N01, and in the actual production process, the profile after extrusion needs to be subjected to solid solution, quenching and artificial aging treatment to obtain a better mechanical property. For example, in the patent application CN107034392A, the raw material is configured by means of alloy element composition, and is subjected to homogenization treatment to obtain a cast blank; the cast blank is subjected to hot extrusion at an extrusion speed of 1.5-2 mm / s, and the outlet temperature of the hot extrusion is 510℃ or higher, and is subjected to on-line quenching to obtain an extruded profile; the extruded profile is subjected to aging treatment, which can obviously improve the microstructure property and alloy plasticity of the aluminum alloy material. However, the profile for rail transit vehicles has a length of 26-30 meters, and the general solid solution and quenching equipment cannot meet the size requirements, and the construction of a long profile heat treatment equipment has a high cost and maintenance cost, resulting in a long profile delivery cycle and high cost.

[0003] In view of this, the present application is proposed. SUMMARY

[0004] Carbon nanotubes have a small size and high thermal stability, and are often used to adjust the mechanical property of an alloy material. For example, in the Chinese patent application 201410032834.0, the plasticity of an aluminum magnesium silicon manganese alloy is increased by means of carbon nanotubes, but the aluminum magnesium silicon manganese alloy in the scheme is similar to the 6N01 aluminum alloy in the present application, and even if the raw material composition is optimized, the preparation process still needs to be further subjected to heat treatment at a high temperature after the extrusion process. For example, in the Chinese patent application 201410032834.0, the aging treatment is performed at 170℃. The temperature of the aging treatment is related to the type of the aluminum alloy, and for the 6N01 aluminum alloy in the present application, the alloy composition content is low, and it belongs to a medium-low strength aluminum alloy series, and the aging treatment is indispensable. For example, the necessity of the heat aging is listed in detail in the article “Influence of Heat Aging on Performance Uniformity of 6N01 Aluminum Alloy Profile”.

[0005] In order to solve the defects of long delivery cycle and high cost of long profiles caused by quenching / thermal aging of 6N01 aluminum alloy in the prior art, the application provides a heat treatment-free 6N01 aluminum alloy and a preparation method and application thereof, specifically, by redesigning alloy components, replacing trace alloy elements with carbon nanotubes and simplifying components, it is accidentally found that this way can not only obtain ultra-fine grain structure to improve the mechanical properties of the profile, but more importantly, the alloy components can maintain excellent mechanical properties of the profile under the heat treatment-free process, in other words, the heat aging treatment has almost no effect on the strength of the aluminum alloy of the application, and the method of the application can overcome the technical prejudice that heat aging treatment must be performed in the field, which can greatly shorten the delivery cycle and reduce the cost for the 6N01 aluminum alloy long profile with a single length of 26-30 meters for high-speed rail, and has good practical engineering significance and economic value.

[0006] Specifically, the application provides a 6N01 aluminum alloy, which is an extruded profile containing ultra-fine grain structure obtained by compacting, sintering, extruding and aging treatment of composite powder cold welding particles.

[0007] The composite powder cold welding particles are obtained by ball milling of a composite powder composed of aluminum powder and carbon nanotubes with Mg and Si, and the aging treatment refers to transient aging precipitation during natural cooling after alloy phase extrusion; wherein the content of Mg in the composite powder cold welding particles is 0.5-0.7wt%, the content of Si is 0.6-0.7wt%, the content of carbon nanotubes is 0.5-1.2vol%, and the content of other trace alloy elements is not higher than 0.5wt%.

[0008] The technical principle of the application is as follows: 1) the carbon nanotubes have small size and high thermal stability, the grain structure of the obtained 6N01 aluminum alloy is ultra-fine grain, and the rich grain boundaries and interfaces are beneficial to the dispersion precipitation of Mg2Si alloy phase and obtaining high strength; 2) by replacing Cu, Fe, Mn, Cr and other trace alloy elements with carbon nanotubes, the alloy components are simpler, which is beneficial to obtaining high strength and toughness and fatigue performance; 3) the ultra-fine grain structure and the simplified trace alloy elements promote the transient aging precipitation of the alloy phase during the natural cooling process after profile extrusion, thereby achieving the purpose of heat treatment-free.

[0009] According to the 6N01 aluminum alloy provided by the application, the trace alloy elements include Cu, Fe, Mn, Cr, Zn and Ti, and the content of each element in the composite powder cold welding particles is respectively: Cu < 0.15%, Fe < 0.15%, Mn < 0.10%, Cr < 0.10%, Zn < 0.10% and Ti < 0.10%.

[0010] The carbon nanotube is a multi-walled carbon nanotube, the diameter is 5-50nm, and the length is 0.2-10um.

[0011] The extruded profile is a long profile with a single length of 26-30m.

[0012] The application further provides a preparation method of the 6N01 aluminum alloy.

[0013] The composite powder composed of aluminum powder and carbon nanotube is ball milled with Mg and Si at a rotating speed of 110-350rpm for 0.5-2h to obtain composite powder cold welding particles;

[0014] The 6N01 aluminum alloy is obtained by cold pressing, sintering and extruding the composite powder cold welding particles, and then performing natural cooling, i.e. transient aging.

[0015] The composite powder is obtained by ball milling aluminum powder and carbon nanotube at a rotating speed of 40-100rpm for 5-24h.

[0016] The preparation method of the 6N01 aluminum alloy further comprises the step of cold pressing, cold pressing or cold isostatic pressing the green compact.

[0017] The sintering is vacuum sintering, pressure sintering, pressureless sintering, atmosphere protection sintering or hot isostatic sintering, preferably, the sintering temperature is 500-600℃, and the sintering time is 2-6h.

[0018] The extrusion is hot extrusion, and the extrusion temperature is 450-520℃, and the extrusion ratio is 16-100.

[0019] The application further provides the use of the 6N01 aluminum alloy in high-speed rail.

[0020] The application provides a heat treatment-free 6N01 aluminum alloy, a preparation method and use thereof, the alloy component is redesigned, the carbon nanotube replaces trace alloy elements, and the component is simplified, unexpectedly, it is found that this way can not only obtain ultrafine grain structure to improve the mechanical property of the profile, but also can keep the mechanical property of the profile from decreasing under the heat treatment-free process, which can greatly shorten the delivery cycle and reduce the cost for the 6N01 aluminum alloy long profile with a single length of 26-30m used in high-speed rail, and has good practical engineering significance and economic value. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0022] Figure 1 is a structural comparison diagram of a conventional 6N01 alloy and the heat treatment-free 6N01 alloy provided by the present application. DETAILED DESCRIPTION

[0023] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely in combination with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0024] The present application will be described below in combination with Figure 1 a heat treatment-free 6N01 aluminum alloy and a preparation method and application thereof.

[0025] Embodiment 1

[0026] A preparation method of a 6N01 aluminum alloy, comprising the following steps:

[0027] Step 1): 39.1 g of aluminum powder is ball milled with 400 g of multi-walled carbon nanotubes (diameter of 5-10 nm, length of 0.5-2 μm) at a speed of 80 revolutions per minute for 8 hours to obtain a composite powder;

[0028] Step 2): the composite powder is uniformly mixed with 243 g of Mg powder and 257 g of Si powder, and then ball milled at a speed of 200 revolutions per minute for 1 hour to obtain composite powder cold welding particles; the alloy composition in the composite powder cold welding particles is 0.65 wt% of Mg and 0.6 wt% of Si, and there is no other trace alloying element; the content of carbon nanotubes is 1.2 vol.%.

[0029] Step 3): after the composite powder cold welding particles are pressed, sintered and extruded, the 6N01 aluminum alloy extruded profile is obtained by instantaneous aging precipitation during the natural cooling process, and a structural comparison diagram of the 6N01 aluminum alloy extruded profile and a conventional 6N01 alloy is shown in Figure 1 .

[0030] Embodiment 2

[0031] A 6N01 aluminum alloy, the steps of which are basically the same as those of Example 1, except that the multi-walled carbon nanotubes used have a diameter of 30-50 nm and a length of 5-10 μm.

[0032] Comparative Example 1

[0033] A 6N01 aluminum alloy, the main preparation method of which is a powder metallurgy method, comprising the following steps:

[0034] Step 1): 39.1 g of aluminum powder and 400 g of multi-walled carbon nanotubes (diameter 5-10 nm, length 0.5-2 μm) are ball milled at a speed of 80 rpm for 8 hours to obtain a composite powder;

[0035] Step 2): The composite powder is uniformly mixed with 243 g of Mg powder and 257 g of Si powder, and then ball milled at a speed of 200 rpm for 1 hour to obtain a composite powder cold welding particle; the alloying components of the composite powder cold welding particle are 0.65 wt% Mg and 0.6 wt% Si, and there are no other trace alloying elements; the content of carbon nanotubes is 1.2 vol.%.

[0036] Step 3): The composite powder cold welding particle is pressed, sintered and extruded to obtain an extruded profile.

[0037] Step 4): The extruded profile is solution treated at 540°C for 3 hours, then water quenched at room temperature, and then aged at 170°C for 12 hours to obtain a 6N01 aluminum alloy extruded profile.

[0038] Comparative Example 2

[0039] A 6N01 profile is obtained by a casting method, and the main alloying components of the 6N01 ingot are 0.65 wt% Mg and 0.6 wt% Si; the 6N01 ingot is quenched online after being extruded from an extrusion port at 540°C, and then aged at 170°C for 8 hours.

[0040] Table 1

[0041]

[0042]

[0043] As can be seen from Table 1, the carbon nanotubes significantly improve the application performance of the 6N01 profile, and when the difference between Example 1 and Comparative Example 1 is only in step (4), the performance of Example 1 is equivalent to that of Comparative Example 1, meeting the requirements of practical application, which shows that the 6N01 profile obtained by the method in the present application is greatly reduced in the influence of heat treatment and thermal aging and other treatment processes, and the 6N01 profile can be directly applied in the required field without depending on the heat treatment and thermal aging and other treatment processes, especially for the 6N01 aluminum alloy long profile with a single length of 26-30 meters for high-speed rail, the delivery cycle can be greatly shortened, and the cost can be reduced, which has good practical engineering significance and economic value.

[0044] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of producing a 6N01 aluminium alloy characterised in that, The preparation method comprises: ball-milling a composite powder composed of aluminum powder and carbon nanotubes with Mg and Si at a rotating speed of 110-350 rpm for 0.5-2 h to obtain composite powder cold-welding particles; the composite powder is obtained by ball-milling aluminum powder and carbon nanotubes at a rotating speed of 40-100 rpm for 5-24 h; the content of Mg in the composite powder cold-welding particles is 0.5-0.7 wt%, the content of Si is 0.6-0.7 wt%, the content of carbon nanotubes is 0.5-1.2 vol%, and the content of other trace alloying elements is not higher than 0.5 wt%; after compacting, sintering and extruding the composite powder cold-welding particles, the 6N01 aluminum alloy is obtained in a natural cooling process, i.e. transient aging precipitation, and the 6N01 aluminum alloy is an extruded profile.

2. The method of making the 6N01 aluminum alloy of claim 1, wherein, The trace alloying elements include Cu, Fe, Mn, Cr, Zn and Ti, and the content of each element in the composite powder cold-welding particles is: Cu < 0.15%, Fe < 0.15%, Mn < 0.10%, Cr < 0.10%, Zn < 0.10% and Ti < 0.10%.

3. The method of producing the 6N01 aluminum alloy according to claim 1 or 2, characterized by, The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 5-50 nm and a length of 0.2-10 μm.

4. The method of producing the 6N01 aluminum alloy according to claim 1 or 2, characterized by, The extruded profile is a long profile with a single length of 26-30 meters.

5. The method of making the 6N01 aluminum alloy of claim 3, wherein, The extruded profile is a long profile with a single length of 26-30 meters.

6. The method of making the 6N01 aluminum alloy of claim 1, 2, or 5, wherein, The compact is die-pressed, cold-pressed or cold isostatic pressed.

7. The method of claim 3, wherein the 6N01 aluminum alloy is prepared by the steps of: The compact is die-pressed, cold-pressed or cold isostatic pressed.

8. The method of claim 4, wherein the 6N01 aluminum alloy is prepared by the steps of: The compact is die-pressed, cold-pressed or cold isostatic pressed.

9. The method of making the 6N01 aluminum alloy of any of claims 1, 2, 5, 7-8, wherein, The sintering is vacuum sintering, pressure sintering, pressureless sintering, atmosphere protection sintering or hot isostatic sintering.

10. The method of claim 9, wherein the 6N01 aluminum alloy is prepared by, The sintering temperature is 500-600 ℃, and the sintering time is 2-6 h.

11. The method of claim 3, wherein the 6N01 aluminum alloy is prepared by the steps of: The sintering is vacuum sintering, pressure sintering, pressureless sintering, atmosphere protection sintering or hot isostatic sintering.

12. The method of claim 4, wherein the 6N01 aluminum alloy is prepared by the steps of: The sintering is vacuum sintering, pressure sintering, pressureless sintering, atmosphere protection sintering or hot isostatic sintering.

13. The method of claim 6, wherein the 6N01 aluminum alloy is prepared by the steps of: The sintering is vacuum sintering, pressure sintering, pressureless sintering, atmosphere protection sintering or hot isostatic sintering.

14. The method of producing the 6N01 aluminum alloy according to any one of claims 11 to 13, characterized by, The sintering temperature is 500-600 ℃, and the sintering time is 2-6 h.

15. The method of making the 6N01 aluminum alloy of any of claims 1, 2, 5, 7-8, 10-12, wherein the method further comprises, The extrusion is hot extrusion, and the extrusion temperature is 450-520 ℃, and the extrusion ratio is 16-100.

16. The method of claim 3, wherein the 6N01 aluminum alloy is prepared by the steps of: The extrusion is hot extrusion, and the extrusion temperature is 450-520 ℃, and the extrusion ratio is 16-100.

17. The method of claim 4, wherein the 6N01 aluminum alloy is prepared by the steps of: The extrusion is hot extrusion, and the extrusion temperature is 450-520 ℃, and the extrusion ratio is 16-100.

18. The method of claim 6, wherein the 6N01 aluminum alloy is prepared by the steps of: The extrusion is hot extrusion, and the extrusion temperature is 450-520 ℃, and the extrusion ratio is 16-100.

19. The method of claim 9, wherein the 6N01 aluminum alloy is prepared by, The extrusion is hot extrusion, and the extrusion temperature is 450-520 ℃, and the extrusion ratio is 16-100.

20. The method of claim 14, wherein the 6N01 aluminum alloy is prepared by, The extrusion is hot extrusion, and the extrusion temperature is 450-520 ℃, and the extrusion ratio is 16-100.

21. A 6N01 aluminium alloy characterised in that, The extruded profile is an extruded profile obtained by compacting, sintering, extruding and aging treatment of the composite powder cold-welding particles; and is prepared by the preparation method of the 6N01 aluminum alloy in any one of claims 1-20.

22. Application of the 6N01 aluminum alloy in claim 21 in high-speed rail.

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